1. Field of the Invention
The present invention relates to a windshield wiper in which the included angle between inboard and outboard positions or the operative sweep of the wiper can be changed, and more particularly to a wiper system including a compact motor fixed to a stationary member and operable to vary the operative sweep of the wiper.
2. Description of the Related Art
It is well known to vary the included angle between inboard and outboard positions of a windshield wiper. FIG. 35 shows the basic principle of varying the included angle between inboard and outboard positions of a wiper. An eccentric shaft 201 is driven for rotation by a motor. A crankshaft 202 is mounted to the eccentric shaft 201 and selectively movable relative thereto. A crank lever 203 has one end fixed to the crankshaft 202. The other end of the crank lever 203 is pivotally connected to one end of a rod 204. The other end of the rod 104 is pivotally connected to a free end of an arm 207 which is, in turn, fixedly mounted to a pin 205. The pin 205 is rotatably supported by a stationary member and is adapted to carry a wiper arm 206.
When the center of the crankshaft 202 is positioned, as indicated by the circle 202', relative to the center of the center of the eccentric shaft 201, the other end of the crank lever 203 is rotated about the axis of the eccentric shaft 201 as shown by the double circle 203'. At this time, the arm 207 is rotated about the pin 205 through a predetermined angle. In order to place a wiper blade (not shown) in its depressed park or stowed position, the crankshaft 202 is moved relative to the eccentric shaft 201 in such a manner that its center is displaced as indicated by the triangle 202". As a result, the other end of the crank lever 203 is moved toward the axis of the eccentric shaft 201 as shown by the triangle 203". Also, the arm 207 is moved to its stowed position as shown by the triangle 207". The wiper arm 206 can be moved to the stowed position below the inboard position by displacing the crankshaft 202 relative to the eccentric shaft 201.
The wiper arm is oscillated back and forth to wipe, for example, a windshield when the vehicle is not only stopped, but also runs at any speed. While the vehicle is running, the force of wind is exerted on the wiper arm 206. This causes the wiper arm 206 to move beyond a predetermined position and thus, increases a predetermined arcuate path along which the wiper arm 206 is moved. Such undesirable movement of the wiper arm 206 results in the damage of a wiper blade due to contact with a piller. If the wiper blade is moved beyond the piller, then it becomes even inoperative.
The force of wind increases through the arm 207, the crank lever 203 and the rod 204, and then acts on the motor. To this end, a large worm is required to counteract such a force. This results in an increase in the size of the overall wiper system.
For the foregoing reasons, the prior art wiper drive mechanism is large, and the wiper is subject to damage.
Accordingly, it is an object of the present invention to provide a windshield wiper which overcomes the foregoing problems encountered in the prior art.